The present invention generally relates to physiological measurements, and more particularly relates to controlling devices based on physiological measurements.
Manufacturers of environmental devices such as HVAC (heating, ventilating, and air conditioning) equipment are attempting to make the systems they manufacture more efficient. Efficiency requirements are driven by rising energy costs, and have more recently been driven by increased awareness of environmental issues. There are several methods for making HVAC systems more efficient. One method for achieving energy efficiency in central HVAC systems is by introducing zones that are controlled by multiple thermostats. This allows a more granular application of heat, similar to non-central heating systems. The rationale behind this method is avoiding the expense of heating or cooling in unneeded zones or areas. Another method is to employ heat exchangers to recover sensible or latent heat from exhausted air. This is done by transfer of energy to the incoming outside fresh air. The rationale behind this method is also avoidance, namely reducing the amount of time the system is actively working. However, conventional methods for controlling environmental devices are generally based on temperature readings, timers, and/or user activation signals. This can lead to the inefficient and over-use of the devices.